Railroad companies must perform maintenance on their tracks and other infrastructure associated with their rail lines. The railroad companies employ many different types of rail mounted vehicles to accomplish such maintenance, and these vehicles can range widely in their size, weight and shape because the vehicles perform a variety of tasks. These vehicles may be employed in one or more work gangs, each work gang including anywhere from four to forty vehicles. As such, many vehicles may be working in close proximity on a single track.
The speed at which the work gang is traveling, and each vehicle within the gang, can vary widely at any given time. For example, the work gang may be traveling to a work site, in which case the work gang, and each vehicle, is traveling at a higher rate of speed than when the vehicles are working at a worksite. When the vehicles are working at a work site, each vehicle is generally traveling at a lower rate of speed or not at all. Within a work gang, the speeds of the vehicles may vary depending on the task that each vehicle is performing.
Railroads have had several severe collisions and other accidents, some resulting in fatalities, when adequate spacing has not been maintained between rail mounted vehicles. Railroad companies now require that a specific spacing be maintained between vehicles when traveling to/from work sites and when working at a work site.